As discussed in U.S. Pat. No. 3,827,740 issued Aug. 6, 1974 to Richard R. Golze et al for a "Structurally Reinforced Vehicle Bumper", it is well known to form an external bumper member so that it has a generally rectangular or box-shaped cross section. It was further pointed out that the "structural strength, and hence the deformation resistance, of the box-shaped bumper greatly may be increased by the addition of a reinforcing member extending from the inner surface of the outermost bumper wall that will be impacted as during a minor vehicle collision and the wall of the bumper opposite the impact wall."
Since the aforementioned patent issued in 1974, there have been radical changes in automobile vehicle design parameters. Fuel efficient automobiles have become the objective of all automobile manufacturers. One way to increase miles per gallon is to reduce the weight of the vehicle components. Vehicle bumpers in particular have been prime candidates for weight reduction programs. It is, therefore, inconsistent with weight reduction objectives to seek increased structural strength by the addition of reinforcing members to a bumper structure.
It has been suggested that aluminum alloys be substituted for the cold rolled steel from which bumpers conventionally have been fabricated. Although aluminum bumpers weigh less than comparable steel bumpers, a substantial cost penalty is incurred with the use of aluminum alloys. High strength, low alloy steels also have been suggested as well as the use of fiberglass plastic materials.
An analytical approach to bumper system design has established the following considerations that must be satisfied appearance, cost, weight, performance, design flexibility, aerodynamics, engine cooling capacity and manufacturability within current capabilities of the manufacturer. Steel remains the prefered material for meeting the desideratum in bumper design and manufacturing feasibility.
Application of an analytical approach results in a bumper that represents an improvement over known high strength, low alloy, lightweight steel bumpers. The bumper system is one that has reduced assembly complexity, reduced weight and reduced cost.